From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH][RFC]: mutex: adaptive spin
Date: Tue, 06 Jan 2009 22:44:35 +0100
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Cc: Gregory Haskins <ghaskins@novell.com>, Ingo Molnar <mingo@elte.hu>,
	Matthew Wilcox <matthew@wil.cx>,
	Andi Kleen <andi@firstfloor.org>,
	Chris Mason <chris.mason@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-btrfs <linux-btrfs@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Steven Rostedt <rostedt@goodmis.org>,
	Nick Piggin <npiggin@suse.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Morreale <pmorreale@novell.com>,
	Sven Dietrich <SDietrich@novell.com>
To: paulmck@linux.vnet.ibm.com
Return-path: <linux-btrfs-owner@vger.kernel.org>
In-Reply-To: <20090106214229.GD6741@linux.vnet.ibm.com>
List-ID: <linux-btrfs.vger.kernel.org>

On Tue, 2009-01-06 at 13:42 -0800, Paul E. McKenney wrote:
> Preemptable RCU needs to be faster.  Got it -- and might have a way
> to do it by eliminating the irq disabling and cutting way back on the
> number of operations that must be performed.  It would probably still
> be necessary to access the task structure.
> 
> Or is something other than the raw performance of rcu_read_lock() and
> rcu_read_unlock() at issue here?

With Linus' mutex_spin_or_schedule() function the whole - keeping
owner's task_struct alive issue goes away,.. now if only the thing would
boot...